For optimum heating by the aid of thermostatically controlled electric heating cooking plates or hobs it is desired that the maximum power is on as long as possible without the plate being warmer than necessary when the load has reached the cooking temperature. Earlier known thermostats operate in a way such that they switch off the power when a measured temperature T.sub.F reaches a pre-set value. This temperature T.sub.F is a combination of the temperature T.sub.P of the cooking plate and the temperature T.sub.k of the cooking utensil, the ratio of combination being greatly dependent on the bearing of the cooking utensil against the cooking plate represented by the thermal resistance R.sub.pk and the magnitude m.sub.v of the load (the thermal mass of the load). Thus, the moment at which the power is switched off will not always be the optimum one but may vary.